Traditionally, room-by-room heating, and air conditioning systems in large buildings have been what are known in the art as four-pipe fan-coil systems. The four-pipe fan-coil system consists of a separate cooling plant and a separate heating plant. The cooling plant supplies cold water through a first dedicated piping system that circulates the cold water throughout the building. Similarly, the heating plant supplies hot water through a separate second dedicated piping system for circulation throughtout the building. Individual fan-coil units placed at various locations throughout the building provide for zonal temperature control. Heating or cooling is provided by having the fan circulate air over a coil that is accessing either the hot-water or the cold-water piping system, respectively. While the four-pipe fan-coil system provides zonal temperature control, economy of operation, low maintenance, and minimum noise, the relatively high cost of constructing the dedicated hot and cold-water piping systems reduces their popularity.
To avoid the high cost of the four-pipe fan-coil systems, one prior art fan-coil system utilizes a single dedicated cooling/heating piping system. The single piping system may either carry heating water or cooling water. One disadvantage of the system is that the entire building must be either heated or cooled. While in some applications this restriction is acceptable, it can be appreciated that, in large buildings, portions of the building may require cooling while other portions of the building require heating.
A combination air conditioning and fire suppression system is shown in U.S. Pat. No. 3,939,914 to Carroll. A cooling plant and a heating plant are connected to a single piping system. The piping system is also used for fire suppression purposes. However, because only a single piping system is utilized, the water flowing therein must be a single temperature. Thus, in order to selectively heat and cool different zones of the building, a plurality of compressor-type heat exchangers must be located throughout the building. The use of the compressor-type heat exchangers allows heating or cooling from a single-temperature fluid. However, compressor-type heat exchangers are costly, require high-maintenance, and are relatively noisy.
The present invention solves these problems and others by utilizing separate heating and cooling piping systems. The cooling piping system is shared with the fire sprinkler piping system in the case of cold water and, in the case of hot water, the heating piping system is shared with the domestic hot-water piping system. By having two separate piping systems, specific zonal control of temperature can be achieved by the use of simple fan-coils. Moreover, because the piping systems are coincident with existing building systems, it can be appreciated that the cost of installing such a heating and cooling system is relatively low.